Sifter



April 7, 1925. 1,532,720

E. 5. SMITH SIFTER Filed June 1, 1923 ATTORNEYS Patented 7,

units stars-s rareurrrict.

EDMlJ'ND S. SMITH, OF LA SALLE, NEW YORK, ASSIGNQR TO THE CARIORUNDUM COM- ?ANY, OF NIAGARA FALLS, NEW YORK, A COR-POBATIGN OF PENNSYLVANIA.

SIFTER.

Application filed June 1, 1923. Serial l lo. 642,774.

To all whom it may concern Be it known that I, EDMUND S. SMITH, a citizen of the United States, residing at La Salle, in the countyof Niagara and State of New York, have'invented certain new and useful Improvements in Sifters, of which the following is a specification, reference being-had therein to the accompanying drawings.

The present invention relates to improvements in sifters or grading machines for granular or pulverized material.

ln machines of this character, the material s caused to pass over reciprocating screens of varying mesh for the purpose of dividing the mass up into 1ts dliferent sizes or grades. Heretofore the screen frames have usually either been supported on inclinedguides or suspended from above by means of movable straps or other flexible means The reciprocating motion has customarily been imparted to the screens by means of eccentrics mounted .on' a horizontal shaft and operatively connected to the screens by connecting rods, the latter having a throw,

in a vertical plane. Such guides or other means of support are sub ect to cons1derable wear and a umping motion is often imparted to the screens by the vertical travel of the connecting rods or by lost motion in the variousjoints of the supporting or driving members.

By the present invention 1 have provided a sifter in which each screen is caused to oscillate smoothly in a fixed plane by means comprising an eccentric and connect ing rod moving in substantially the same plane as the screen and in which each screen is maintained in this plane without the use of parts subject to wear. By reason of this construction, I am enabled to impart to the screens the necessary reciprocating motion with a minimum amount of vibration, and this is a very important con sideration, since vibration seriously interferes with accuracy of grading.

In the accompanying drawings I have shown, for purposes of illustration only, one embodiment of the present invention, it being understood that the drawings do not define the limits of the invention, as changes may be made in the construction and operation therein disclosed without departing from the spirit of the invention or scope of my broader claims.

In the drawings: I Figurel is av sideelevation of a slfter em bodying my invention;

Figure 2 is a horizontal sectional view on the line Ill1 of Figure 1, illustrating one of the screens in plan and the flexible suspension means for sald screen; and

Figures 3 and t are views illustrating shaft 5, each of said eccentrics being operatively connected to a screen boX 9 by means of a connecting rod 10 and yoke 11.

Each screen box 9 comprises a tray 12and a readily detachable screen frame 13. Each screen is provided with a discharge hopper letat the lower end thereof through which is discharged all of the material remain-ing on the screen, while that passing through the screen falls into the tray therebeneath and is carried down to the head of thewnext lower screen. Each screen box may be supported at the mid-point at each end by means of a flexible metal or wooden strap 15, each strap being attached at one end by a shackle 16 and at the other end by a hinged joint 17 to brackets 18 carried by vertical members of the frame 2, whereby each screen frame is maintained absolutely in one plane but is permitted to oscillate freely back and forth. The movement of the eccentrics causes a lateral reciprocating motion of the screen boxes and frames, bending or flexing the straps 15, the resultant shortening of which is compensated for by the shackles 16. The rapid lateral reciprocating motion thus imparted to the screens results in an extremely smooth and evenly distributed flow of the granular -ma terial upon their surfaces. These In Figures 3 and t, are shown other forms of screen box suspension members 15 and 15 which may be substituted for the straps 15 and connecting parts 16, 17 and 18, the ends of said members being secured rigidly to the vertical members of the supporting frame 2. In such case the elasticity of the material used, which may be spring steel strip, obviates the necessity for the shackles l6 and hinged joints 17.

In mounting the eccentrics on the vertical shafts, I prefer to mount the eccentrics of the screens driven from the same shaft at an angle of 180 to each other and the vertical shafts are preferably driven at equal speeds by the above described driving means. The reciprocating movements of the screens operated by one vertical shaft are timed so that they exactly balance the reciprocating motions of the screens operated by the other vertical shafts. In this manner vibration of the supporting frame is reduced to a minimum.

The operation is substantially as follows:

From the feed hopper (not shown), the granular material to be graded is fed on at the head of the top screen. Oversize material flows down the screen and is carried off through the discharge hopper 14; and conducted away through properly arranged pipes (not shown). The line material passes through the screen to the tray 12 and flows to the head of the screen below. This screen, being finer, takes the coarser material and discharges it from the machine while the fines pass down to the succeeding screen. In this manner a succession of grades or sizes is obtained, the number, of course, being dependentupon the number of screens employed, eight making a conveniently operated machine. For scalping only two or three screens would be required. By removing the coarser material first the wear on the finer screens is greatly reduced and at the same time their capacity, which is necessarily less than that of the coarser screens, is not overtaXed, since each succeeding screen has to handle less material than its predecessor.

The advantages of the present invention arise from the novel manner in which the screens are supported and operated, whereby smooth and uniform operation of the screens is secured, enabling accurate grading of the material.

I claim:

1. A sifter comprising a vertically er;- tending main supporting frame, a screen, a horizontally extending flexible member attached to each end of said screen, each of said members being attached at its medial portion to said screen and at its ends to said frame, permitting motion of said screen in a single plane only, and means for reciprocating said screen in a rectilinear path, comprising an eccentric mounted on a vertical driving shaft and means connecting said eccentric to one end of said screen, substantially as described. 7

2. A shifter comprising a main supporting frame, a screen, a horizontally extending fl :rible member attached to each end of said screen for individually supporting the screen, each of said members being attached at its medial portion to said screen and at its ends to said frame by means of hinges, permitting motion of said screen in a single plane only, and means for reciprocating said screen, said means exerting thrust on said screen in the direction of movement of the screen only, substantially as described.

3. A sifter comprising a main supporting frame, a screen, a horizontally extending flexible member attached toeach end of said screen for individually supporting the screen, each of said members being attached at its medial portion to said screen and at its ends" to said frame by means of hinges, one of said hinges being a double hinge or shackle, and means for reciprocating said screen, said means exerting thrust on said screen in the direction of movement of the screen only, substantially as described.

at. A s ifter comprising a main supporting frame, a plurality of superposed screens, a horizontally extending flexible member attached to each end of each screen, each of said members being attached at its medial portion to a screen and pivotally connected at its ends to said frame, permitting motion of each screen in a single Plane only, and means for reciprocating said screens, substantially as described.

5. A shifter comprising a main supporting frame, a plurality of superposed screens, an elastic strip attached to each end of each screen, each of said strips being rigidly attached at its medial portion to the screen and pivotally connected at its ends to said frame, permitting motion of each screen in a single plane only, and means for reciprocating said screens, the reciprocating movements of the screens being balanced to reduce vibration of the supporting frame, substantially as described.

6. A sifter comprising a main supporting frame, a plurality of screens, a flexible member rigidly attached at its medial portion to each end of each screen, each of said men1- bers being attached at its ends to said frame, permitting motion of each screen in a single plane only, and means for reciprocating said screens, comprising two vertical driving shafts on which are mounted eccentrics each attached to a corresponding screen by a connecting rod whereby each screen is driven from one shaft only, alternate screens being driven from the same vertical shaft, substantially as described.

7. A sifter comprising a main supporting frame, a plurality of screens, a flexible member rigidly attached at its medial portion to each end of said screen, each of said members being attached at its ends to said frame, permitting motion of each screen in a single plane only, and means for reciprocating said screens, comprising two vertical driving shafts driven at the same speed from a common driving member and on which are mounted eccentrics each attached to a corresponding screen by a connecting rod whereby each screencis driven from one shaft only, alternate screens being driven from the same vertical shaft, and the reciprocation of the screens driven from one vertical shaft being timed to balance the reciprocation of the screens driven from the othervcrtical shaft, substantially as described.

In testimony whereof I have hereunto set my hand.

EDMUND s. SMITH. 

